Coherent 3.0

I don’t know why I was so dumb as a kid, but I remember thumbing through various magazines, and always seeing this ad:

Coherent Ad

And isn’t that sounding great? Lex, Yacc, UUCP, and UNIX functionality on a AT compatible machine for $99! And then you see reviews like this one from PC Mag:

Now even if you want to you can’t wind the clock back to the late 1970s, but Unix lovers can do the next best thing-pick up a copy of Mark William’s Coherent for $99.95.

Included in this time capsule are all of the utilities that you would have received in an AT&T Unix, Version 7, distribution circa 1978. The package includes a protected-mode multi-user multitasking operating system. over 150 utility programs, a C compiler, an assembler, software development tools, text formatting tools, system management tools, telecommunications utilities, and complete documentation in a very hefty, 1,000-page, perfect bound book. Most of the Unix classics-grep, ed, sed, awk, lex, sh, emacs-are there as well. The only favorites that are missing are vi (which is a text editor) and Dave Korn’s new shell.

Whether Coherent’s views on the Unix system match your own is a matter of taste. In the halcyon late 1970s, the Unix system was a relatively simple affair-lean and clean, and understandable to mere mortals. Since then, in an effort to make Unix the universal solution, countless features and versions have been grafted onto it by innumerable programmers, managers, committees, and boards of directors.

The result stands in stark contrast to the stated goals of Unix’s inventors. Coherent remains true to Unix’s roots and eschews local area networking, graphical user interfaces, menus, mice, and many of the other amenities that present-day DOS users and Unix users have come to expect of modem software.

Coherent’s installation is painless, but only after the agony of freeing up a 7MB or larger partition on an ordinary MFM or RLL disk, on a classic AT architecture machine. Since they are products of the modem era, ESDI and SCSI disks, as well as IBM’s Micro Channel architecture are not supported. Graphic display adapters are tolerated (used in text mode); mice are not supported. Coherent worked flawlessly, though, on my geriatric AT clone.

Coherent has a dual boot facility, so that you can choose to boot either DOS or Coherent during your startup procedures, but unfortunately you can’t run
DOS software from within the Coherent environment.

Mark Williams’president Robert Schwartz explained that the intended audience for Coherent are people who want to learn about or try the Unix system, without the hefty price tag and steep learning curve of the latest Unix versions. Part of Coherent’s advantage in both simplicity and price stems from its origins as a privately developed “clone” product-therefore no AT&T requirements need be met and no per-copy royalty is paid to AT&T. This gives Mark Williams the freedom to set prices as well as compatibility targets.

But learning Unix from Coherent would be a bumpy road. You could certainly master traditional system administration, learn the utilities. And experiment with Unix software development. But you couldn’t learn about networking or the increasingly important X Windows system. Nor could you realistically use Coherent to automate a small business.

Schwartz promises that future versions of Coherent will support 32-bit operation on the 386, and will likely support tighter integration with DOS, some form of window manager. And local area networking. When that occurs, Coherent will be much more like modem Unix systems and, like modem Unix systems, it will have strayed far from its roots.

And then it seemed to my teenage eyes something pretty underwhelming. So I dove into OS/2, and ignored the idea of having a UNIX like system. I was still happy to finally move onto a 16-bit machine, and the thought of running stuff from the 1970’s wasn’t that appealing. Such missed opportunities. But in the last few years, Coherent has been placed under a 3-clause BSD license.

Over at unix4fun, they did unearth some version 3.0 disks! And yes, it’ll install on PCem/86Box using a 286/386/486 machine. One issue I had was I first tried to install onto a massive 40Mb disk, and it never would reboot after the install correctly. However it works great with a 32Mb or smaller disk. As you can see from Kaare’s review it’ll fit into 7MB of disk space! At least having to either re-partition or worry about dual booting is a thing of the past. The disk images are 5.25 disk images, so re-configure your VM appropriately.

Coherent on PCem

As the advertisement says, the installation is a mere four diskettes! And yes, it really does have a C compiler. You will need a serial number for Coherent 3.0, which took a while to find, but Peter had one, and has been poking me for the last week+ to finally write this up. Oh the number is 130500000. 305/Miami connection? Unlikely, but who knows. Don’t forget to download the hefty manual, Coherent_Revision_8_1992, which is for a later version, but still suitable.

And yes, it feels just like Unix v7. The kernel is tiny, 77kb! It’s really cool for 16-bit era stuff, and really interesting to knock around. I know there is a few more people out there that want fun things for their 286, and Coherent will certainly scratch that itch.

Additionally on the site are the 3.1 and 3.2 updates to give you thinks like Elvis so it doesn’t feel anywhere near as primitive. Installing updates and 3rd party packages is covered on page 736 of the manual, or in short you need to know the magical ‘disk set name’ for everything you want to install. I suppose back then it had stuff like this printed on them.

While a ‘dump’ of the source code has been out there, I haven’t really gone through it, so I thought now would be as good as any to take a look at the kernel. The layout is very similar to v6, so I based this on the file ‘sys1.c’ which appears quite a few times in the trees. Using a MD5 checksum against the files there appears to be no less than 17 duplicated tress or 7 unique kernels, spread over three years.

Phew! Naturally the tree structure drifted, but I went ahead and just did a blind import into my CVS server to take a look. And there really does appear in the 1991 versions to be the remnants of either 2.3.37, 3.2.1. It’s hard to say.

did anyone untangle the source drop? I know it basically arrived 20+ years too late. I just took a peek and there is so much duplication, and so many things actually have version 2.3.37 on them, I get the feeling that the bulk of Coherent actually never really was updated.

Ah, Coherent. I inherited the floppies & manual from someone in 1992 or so, but I only had an 8088 machine at the time.

Now at work, there was an AT class machine sitting unused, but I certainly didn’t have permission to reformat the hard drive. So I studied the manuals, and examined the install disks. I don’t remember the details now, but I managed to figure out how to partially boot a Coherent system just off the install disks, without touching the hard drive.

The experience helped me when I later found about “floppy-only” Linuxes, like “tomsrtbt”. How much of a system CAN you make without touching the hard drive? Anyway, I don’t think I ever fully installed Coherent before I sold it away.

Anyway, made a 1.44 coherent 3.0 live image, if anybody would like to get. It was a hell to made and needed several accidentally left secret hints and handwritten remarks found in scanned coherent documents. And pcem, too. Image had been tested on a real-life 486.

if you want to do a guest post, all you have to do is email me the material and suffer through me trying to get the formatting right. I don’t know what the botox stuff is about, I guess more eye rolling drama.

Such a shame to be so close to being able to use something, but never really able to do so.

I know the feeling, for the longest time I had 32bit envy pretty bad. Id just gotten a 286 part by part, but everywhere I went everyone had at least a 386 or 486, and most of them played solitaire.

Not to mention what a massive PITA re-partitioning was. I was so crazy happy when I finally got a 386sx-16 with a fully populated 4MB motherboard. I could finally run OS/2 2.0 to only find out that 4MB really isn’t enough. And that CGA is really less than satisfactory. I’d helped a re-seller install SCO Xenix 386, and snagged a copy + the license and wow… without any compiler it was absolutely worthless to me.

I did the same, running OS/2 2.0 in 4MB RAM on 486DLC-33. Often I’d edit CONFIG.SYS to set the PROTSHELL= line to run TSHELL, eschewing the Workplace Shell GUI altogether. At the time it worked pretty well, and felt a bit like using DESQview – or a lot like the original OS/2 1.0 task switcher, as I learned many years later.

I was able to run the OS/2 version of Borland C++ 1.0 to build native 32-bit VIO apps in one full-screen window, referring to an INF in another (using a text mode INF viewer) and reading FidoNet mail using Msged in another. Good stuff. 🙂

You should be glad you did not have a C-compiler. ( SCO Xenix-386) I tried the C compiler, ( it was on the dev disks, not the runtime disks ).

Simple programs would compile fine, but as the size grew, it would at first crash… then later it would corrupt your swap partition, ( even when it was on another drive ), and later it would trash your root file system… We even tried to have 4 HDs, one /, one /usr, one /etc, and one swap, and it got further… but at some point… it would always trash the root…

Then the switch to Microport… dear god… the C-compiler could compile anything… it could fill 500k with error messages.

The C compiler for Xenix is Microsoft C 5.0 386. It’s the same one they used to make Windows NT, and OS/2 2.0. It’s very particular in how it likes to do things, but if you don’t try to get fancy, and stick to K&R or if they told you up front it’s Microsoft C, then it’s easier to deal with. There also was a port of GCC to Xenix, which actually isn’t half bad. Although it was version 1.x, and you had to deal with the COFF encapsulation for later OS types, but in straight Xenix version 3, it’s x.out a strange thing not too unlike a.out.

the boot disks for 3.0 were in the post, if I’m not mistaken. Although just installing a full system in PCemu/86Box is far more rewarding.

Looks like PCem on Windows? I’ve build 13.1 on Debian 8 and OSX and then installed COHERENT 3.0 on a 286/25 box, works nicely. Video is here:https://youtu.be/LpVYGQWFrc0

Keep in mind it is a 16bit OS, using 16bit integers for the filesystem stuff. So a filesystem cannot be larger than 65536 * 512 bytes.

Better get the 3.0 manual from unix4fun, the 16bit release is quite different from the 32bit releases.

Not that I like emacs that much, but microemcas in combination with the C compiler options is quite powerful. That was outstanding in 1990, that the compiler opens the source right at the error line in microemacs.

The product id’s aren’t magical at all, just mount a floppy disk read-only and look at it’s root directory. And ‘man install’ has all the nasty details of course.

HDD-less PCs (or disabling hd controllers) might help on hangups – I created a live floppy _1.44M_, see this: http://vm01.unsoft.hu/~np/coherentlive/multiuser.jpg
The above 486 dec laptop has no installed hdd. I am working on a busybox-like stuff in order to not to waste space.

In the meantime I have build a COHERENT 3.2 PCem VM with the complete sources for the whole system. This allows to build 3.2 with a single shell script from the sources on a second HD connected to the VM, which boots the self compiled system after the build is through. This VM is similar to a development system used in 1992 @ MWC, should allow anyone to make whatever changes.

QEMU 3.1.0 now is able to boot 3.2, but still have issues, better use PCem for now.